This invention relates to an operation control system for automotive working vehicles, and more particularly to an operation control system of this kind which enables the operation in a stationary state of working machines driven by PTO shafts of an automotive working vehicle to be performed reliably.
Conventionally, there has been proposed e.g. by Japanese Provisional Patent Publication (Kokai) No. 1-155037 an automotive working vehicle having working machines, such as a lawnmower and a rotary cultivator, mounted on PTO shafts thereof and driven by an engine installed on the vehicle through the PTO shafts.
According to this prior art, the automotive working vehicle has a plurality of PTO shafts to which a driving force is transmitted from the engine through a PTO clutch, and a control system which includes first detecting means for detecting whether or not an operator is seated on the driver's seat, second detecting means for detecting whether or not the transmission system of the vehicle is in a neutral position, third detecting means for detecting whether or not the parking brake is locked, fourth detecting means for detecting whether the PTO clutch is engaged or disengaged, and fifth detecting means for detecting whether or not a PTO shaft for stationary operation is selected out of the PTO shafts, the control system being operable to maintain the engine in operation when it is detected that the driver has left the driver's seat under at least the conditions that the PTO clutch is disengaged and at the same time the transmission system is in neutral position.
In such a conventional automotive working vehicle, a stationary operation is often performed by using the PTO shaft as a drive source e.g. for driving a water pump, while the operator is away from the vehicle. During such a stationary operation, if a person other than the operator improperly touches an operating device of the vehicle to operate the vehicle, e.g. if the person unlocks the parking brake, the engine automatically stops and hence the stationary operation is stopped. On this occasion, if the person relocks the parking brake or starts the starter motor, hurriedly and confusedly, to thereby immediately restart the engine rotating by inertia, the stationary operation is unpreferably restarted though the vehicle has moved from the original position for the stationary operation, possibly to a position unsuitable for the stationary operation, due to unlocking of the parking brake. A similar problem arises in a case where the transmission system of the vehicle has been shifted to a position other than the neutral position while the stationary operation is being performed.
Further, in this prior art, a switch for stationary operation is automatically reset when the driver's seat is occupied, which facilitates changeover from a stationary operation to a normal operation. However, to set the switch for stationary operation, it is necessary to carry out a special complicated operation to prevent the operator from failing to reset the switch, e.g. an operation of lifting the driver's seat so as for the driver to be unable to sit on the seat and setting the switch, which makes it difficult to operate the switch.